package migration

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"

	"github.com/DATA-DOG/go-sqlmock"
)

const createMigrationsTableSQL = `CREATE TABLE IF NOT EXISTS schema_migrations (
		version VARCHAR(100) PRIMARY KEY,
		dirty BOOLEAN NOT NULL DEFAULT TRUE,
		applied_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
	)`

func writeMigration(t *testing.T, name, sqlText string) string {
	t.Helper()
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, name), []byte(sqlText), 0o600); err != nil {
		t.Fatalf("write migration: %v", err)
	}
	return dir
}

func expectCleanState(mock sqlmock.Sqlmock, applied ...string) {
	mock.ExpectExec(regexp.QuoteMeta(createMigrationsTableSQL)).WillReturnResult(sqlmock.NewResult(0, 0))
	mock.ExpectQuery(regexp.QuoteMeta(`SELECT version FROM schema_migrations WHERE dirty = TRUE ORDER BY applied_at DESC LIMIT 1`)).
		WillReturnRows(sqlmock.NewRows([]string{"version"}))
	rows := sqlmock.NewRows([]string{"version"})
	for _, version := range applied {
		rows.AddRow(version)
	}
	mock.ExpectQuery(regexp.QuoteMeta(`SELECT version FROM schema_migrations WHERE dirty = FALSE`)).WillReturnRows(rows)
}

func TestRunAppliesEachMigrationOnce(t *testing.T) {
	dir := writeMigration(t, "001_create_widgets.sql", `CREATE TABLE widgets (id BIGINT PRIMARY KEY);`)
	db, mock, err := sqlmock.New()
	if err != nil {
		t.Fatalf("open sqlmock: %v", err)
	}
	t.Cleanup(func() { db.Close() })

	expectCleanState(mock)
	mock.ExpectExec(regexp.QuoteMeta(`INSERT INTO schema_migrations (version, dirty) VALUES (?, TRUE)`)).
		WithArgs("001_create_widgets.sql").WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectExec(regexp.QuoteMeta(`CREATE TABLE widgets (id BIGINT PRIMARY KEY)`)).
		WillReturnResult(sqlmock.NewResult(0, 0))
	mock.ExpectExec(regexp.QuoteMeta(`UPDATE schema_migrations SET dirty = FALSE, applied_at = CURRENT_TIMESTAMP WHERE version = ?`)).
		WithArgs("001_create_widgets.sql").WillReturnResult(sqlmock.NewResult(0, 1))

	if err := Run(context.Background(), db, dir); err != nil {
		t.Fatalf("first run: %v", err)
	}

	expectCleanState(mock, "001_create_widgets.sql")
	if err := Run(context.Background(), db, dir); err != nil {
		t.Fatalf("second run: %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatal(err)
	}
}

func TestRunLeavesFailedMigrationDirty(t *testing.T) {
	dir := writeMigration(t, "002_broken.sql", `CREATE TABLE broken (id BIGINT); ALTER TABLE missing ADD value INT;`)
	db, mock, err := sqlmock.New()
	if err != nil {
		t.Fatalf("open sqlmock: %v", err)
	}
	t.Cleanup(func() { db.Close() })

	expectCleanState(mock)
	mock.ExpectExec(regexp.QuoteMeta(`INSERT INTO schema_migrations (version, dirty) VALUES (?, TRUE)`)).
		WithArgs("002_broken.sql").WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectExec(regexp.QuoteMeta(`CREATE TABLE broken (id BIGINT)`)).WillReturnResult(sqlmock.NewResult(0, 0))
	mock.ExpectExec(regexp.QuoteMeta(`ALTER TABLE missing ADD value INT`)).WillReturnError(errors.New("missing table"))

	err = Run(context.Background(), db, dir)
	if err == nil {
		t.Fatal("expected migration failure")
	}
	for _, fragment := range []string{"002_broken.sql", "statement 2", "dirty", "manual repair"} {
		if !strings.Contains(strings.ToLower(err.Error()), strings.ToLower(fragment)) {
			t.Fatalf("error %q does not contain %q", err, fragment)
		}
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatal(err)
	}
}

func TestRunStopsWhenDirtyMigrationExists(t *testing.T) {
	dir := writeMigration(t, "003_should_not_run.sql", `CREATE TABLE should_not_run (id BIGINT);`)
	db, mock, err := sqlmock.New()
	if err != nil {
		t.Fatalf("open sqlmock: %v", err)
	}
	t.Cleanup(func() { db.Close() })

	mock.ExpectExec(regexp.QuoteMeta(createMigrationsTableSQL)).WillReturnResult(sqlmock.NewResult(0, 0))
	mock.ExpectQuery(regexp.QuoteMeta(`SELECT version FROM schema_migrations WHERE dirty = TRUE ORDER BY applied_at DESC LIMIT 1`)).
		WillReturnRows(sqlmock.NewRows([]string{"version"}).AddRow("002_broken.sql"))

	err = Run(context.Background(), db, dir)
	if err == nil || !strings.Contains(err.Error(), "002_broken.sql") {
		t.Fatalf("expected dirty migration error, got %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatal(err)
	}
}

func TestSplitStatementsPreservesSemicolonsInsideStrings(t *testing.T) {
	statements, err := splitStatements("INSERT INTO notes(value) VALUES ('a;b'); -- comment\nUPDATE notes SET value = \"c;d\";")
	if err != nil {
		t.Fatalf("split statements: %v", err)
	}
	want := []string{
		"INSERT INTO notes(value) VALUES ('a;b')",
		"UPDATE notes SET value = \"c;d\"",
	}
	if len(statements) != len(want) {
		t.Fatalf("got %d statements, want %d: %#v", len(statements), len(want), statements)
	}
	for i := range want {
		if statements[i] != want[i] {
			t.Fatalf("statement %d = %q, want %q", i+1, statements[i], want[i])
		}
	}
}